Matthew Phillips of the Australian National University and his team have also dismissed previous theories that asserted all large, flightless birds – or ‘ratites‘ – share a flightless common ancestor.

Instead, they propose that species lost the ability to fly independently of one another at around the time dinosaurs became extinct, about 65 million years ago.

Without predation and competition from larger dinosaurs, some species of bird were able to shed the limitations flight imposes on body size and weight to evolve into the species of the order Struthioniformes, which includes ostriches, emus, cassowaries and kiwis.

Flightless birds fattened up

The removal of dinosaur predation and competition for food resources allowed ratites to remain grounded. “Birds tend to lose flight,” says Phillips, “Particularly in island situations, unless it is crucial for finding food or escaping predators.”

A glut of food would have allowed individuals to grow larger, and the lack of predators meant that there would no longer have been the need to fly away from danger.

These factors, along with the high-energy requirements of flight and of maintaining associated wing and pectoral apparatus could have led to the loss of flight altogether, say the researchers.

New genetic evidence, including DNA from the extinct giant moa of New Zealand, has shown that the common ancestor of ratites was a bird similar to today’s tinamous, a native of South America that resembles a quail.

Phillips and his team also found that the moa’s closest living genetic relatives were the tinamous, rather than kiwis, emus or any other ratite as was previously thought. …

Further research is needed, but … the theory already has some strong support, given that some of the earliest ratite fossils – dated at around 40 to 50 million years old – have been found in central Europe.

The fossils themselves were not considered sufficient evidence to rethink the origins of ratites, as they can be difficult to indisputably identify.

Trevor Worthy of the University of New South Wales, a palaeozoologist known for his research on the moa, says that although it is no surprise that ratites are not closely related to one another, confirmation that several species became flightless independently is an important development.

“Ratites aren’t all closely related,” he says. “People just assume that because they’re all big and flightless; but in fact they haven’t shared a common ancestor in 60 to 70 million years.”

Worthy was also aware of the fossilised “flying ostriches in Eurasia,” and was excited to discover more concrete evidence in favour of ostriches and other ratites having first emerged from the northern continents.

Volcanic activity may have led to nearly a third of marine life being wiped out around 100 million years ago, research suggests: here.

August 2011. As Colchester Zoo‘s charity, Action for the Wild, continues work to develop the UmPhafa Private Nature Reserve in South Africa. 10 ostrich have been released onto UmPhafa. Ostrich live in groups of between five and fifty individuals; so a group of ten is perfect. They often travel together with grazing animals, such as zebra and antelope, and it is hoped they will ‘team up’ with some of the resident game: here.

7 thoughts on “Flightless’ birds rise after dinosaur extinction”

Researchers have pieced together a new moa family tree. Picture / NZ Herald

Ancestors of New Zealand’s extinct flightless bird, the moa, probably flew here from South America and then lost the ability to fly home.

New research has found that the moa’s closest cousins were not the Australian emu and cassowary, as previously thought, but a small, quail-like South American bird called the tinamou.

Massey University’s Professor David Penny, co-author of a paper on the issue in the journal Systematic Biology, said the moa’s ancestors probably flew here from South America via Antarctica 30 to 40 million years ago when the southern continents were much closer together than today.

He said they probably lost the ability to fly, and developed into much larger birds up to 3.7m high, when they found no natural predators in the small islands that dotted the sea where New Zealand is today.

“Many different kinds of birds have lost flight, so there is nothing unusual about that,” he said.

“In the Pacific Islands there are well over 100 species of rail alone, the family that includes the pukeko and the takahe, that became flightless in the islands because they haven’t got mammalian predators, and because flight is costly.”

The new research is a collaboration led by former Massey student Dr Matt Phillips, now at the Australian National University, with Dr Penny and his postgraduate students Elizabeth Crimp and Gillian Gibb.

Although moa have been extinct for about 500 years, earlier researchers have worked out their genetic structure from bones preserved in swamps.

The Massey/ANU team has now pieced together their family tree.

Dr Penny said the tinamou, which spend most of their time on the ground but can still fly, were always assumed to be related to the flightless “ratites” such as the moa, kiwi and emu.

Until now it had been thought that the moa’s ancestors must have come to New Zealand about 80 million years ago before the southern continents started to drift apart.

“What happened is that we got into a way of thinking that some people call ‘Moa’s Ark’ – the idea that perhaps New Zealand’s plants and animals were a bit primitive and slow and needed special looking after,” he said.

The finding that the moa’s closest cousins are the tinamou, rather than any other Australasian birds, indicates that they must have come much later – when the only way they could have got here was by air.

“The fact that they flew here means that our birds and animals are more vibrant, more dynamic, than we thought,” he said.

Scientists found about 15 years ago that the kiwi’s closest cousin is the Australian emu, suggesting the kiwi’s ancestor also flew here, from Australia, probably more recently than the moa.

Dr Penny said the genetic evidence suggested that the ratite group began evolving about 80 million years ago, before a huge meteorite dropped in Central America 65 million years ago and wiped out the dinosaurs.

He said the oldest birds of any kind appeared to have evolved in what is now the Australasian part of the ancient continent of Gondwanaland.